STOCKHOLM  Fixing leaky pipes in conurbations from Mexico City to New Delhi is a better way to avert water shortages as the world population grows than costly schemes such as dams, a leading expert said on Monday.

"There is no shortage of water in the world, but there is a crisis of management of water supplies," Asit Bitwas, head of the Third World Centre for Water Management in Mexico City, told Reuters during a meeting of 1,000 experts on water in Stockholm.

"There is enough water, even in the Middle East, if we manage our water properly," Bitwas said, disputing the findings of an new international report that said one in three of the world's people lived in areas where water was in short supply.

He said many developing nations often wrongly put priority on expensive schemes to build dams or divert rivers in a bid to increase supplies. He said that the key was in simpler measures like fixing leaks.

"In nearly all the megacities nearly 40 to 60 percent (of water) never reaches the consumer" because of leaks and poor maintenance, he said.

"It is cheaper to fix your leaks, improve your maintenance systems which you can do in a couple of years rather than build a dam 200 kilometres away," he said. India, Mexico, China and Brazil were all among countries that could benefit.

Bitwas, a Canadian citizen born in India, was to receive the conference's annual $150,000 prize for his research. He said that many experts wrongly claimed that crises or even wars over water were looming. "It's baloney," he said.

Earlier, the International Water Management Institute (IWMI) issued a report saying that a third of the world's population was living in regions with water shortages -- mainly in Africa and Asia.

It said that demand for irrigation, which uses three quarters of all water used by humans, would rise because of factors including more demand to produce crops, for food and for biofuels, from a rising population.

"The positive message is that we can increase the productivity of water," said Frank Risjerberman, head of the IWMI told Reuters. "We will simply have to make do with less."

Bitwas said that bad planning of water use was at the heart of suffering caused by famines, which often happened because of erosion caused by poor management.

Bitwas said that China was likely by 2050 to have surged to become the world's largest economy trailed by the United States, India, Japan and Brazil.

"These new economic giants of the future will need a lot of water," he said. Still, he said any problems were likely to be linked to poor water quality rather than water availability.

"If there is going to be a crisis the problem will be because of continuing deterioration of water quality," he said.